With various types of storage units, such as hoppers, silos and tanks for containing material, a common problem is that by compaction of the material it hangs up in the confined space over extended periods of time. This hang up of the material may considerably reduce the working volume of the storage units. In other situations, the material may compact and solidify to the extent that little of any of the material escapes from the storage unit when the lower portion is opened. Other instances involve a channel in the material forming what is commonly referred to as "rat holeing". An extreme situation is where the material completely plugs the entire cross-section of the storage unit.
Many devices have been provided for assisting in unloading of storage units, such as bins, silos and the like. The common devices used are vibrator elements and/or air blasters which are normally attached to the wall of the silo to loosen the material and assist in bottom discharge from the silo. Other devices use a power driven motor which has a rotary attachment for striking the material hung up in the silo to loosen it and encourage its removal from the silo. These devices are normally lowered by hand from the upper portion of the silo. Should an avalanche occur and trap the power driven motor drawing it downwardly and exerting stress on the silo roof, this can result in the problem of roof collapse if the cable supporting the motor is in some way secured to the roof.
In many instances, the silos contain explosive materials such as coal dust fins, or toxic materials such as cement dust and detergents to name only a few. It can become hazardous for the operator to be present on top of the silo to manually maneouvre devices for lowering through the top of the silo to clean out the hung up material.
According to this invention, apparatus is provided which controls the operation of devices lowered through the top of the silo for cleaning out of the hung up material without requiring the presence of operators at all times.